Apparatus for determining the speed of objects



March 1952 D. F. SHELDON ET AL 2,587,775,

APPARATUS FOR DETERMINING THE SPEED OF OBJECTS Filed May 6, 1950 2 SHEETSSHEET 1 IN VEN TOR. DONALD F. SHELDON BY GEORGE F. JENKENS March 1952 D. FESHELDON ET AL 2,537,775

APPARATUS FOR DETERMINING THE SPEED OF OBJECTS Filed May 6, 1950 2 SHEETS-SHEET 2 INVENTOR. DONALD E SHELDON GEORGE E JENKENS ATTORNEY Patented Mar. 4, 1952 UNITED APPARATUS FOR DETERMINING THE SPEED OF OBJECTS Donald F. Sheldon and George F. Jenkins,

' Minneapolis, Minn.

Application May 6, 1950, Serial No. 160,482

Claims.

Our invention relates to apparatus for determining the speed of an object and more particularly to improved apparatus for sensing the presence of an object, such as a thrown ball, at spaced points with means to determine the speed of the object between the spaced points.

There are numerous types of apparatus to measure the speed of an object, but all are subject to various disadvantages, such as complexity of design, inability to withstand rugged usage, and the requirement that the object be accurately directed or propelled. Other apparatus of this general nature require the destruction or disassembly of parts of the apparatus in order to sense the presence of the object and determine its speed, thereby prohibiting multiple measurements without reassembly or rebuilding of the apparatus.

The present invention provides a speed measuring apparatus for a thrown or' freely-propelled object which is capable of sensing the presence of the object over a large plane area at spaced points, the sensing portion of the apparatus controlling an interval measuring portion of the apparatus to measure the objects speed. The sensing portion of the apparatus is adapted to be physically contacted by the object as it passes between spaced measuring points without damaging or disassembling the sensing apparatus, thereby eliminating reassembly or repair and providing for repeatability or multiplicity of measurements. Further, the subject apparatus does not require that the object be accurately directed. The sensing portion of the apparatus includes a pair. of spaced gridworks or sensing members, or one gridwork and a backstop member, each of which are adapted to be contacted by the object and when contacted, operate controlling means for an. interval timer. The elapsed time interval, as the object passes between the gridworks or gridwork and backstop which are spaced apart a predetermined distance, is a measure of the speed of the object between the spaced gridworks or sensing members- It is therefore an object of this invention to provide an improved apparatus for measuring the speed of an object.

It is also an object of this invention to provide improved apparatus for sensing the presence of anobject at spaced points along its line of travel.

It is further an object of this invention to pro vide apparatus for sensing the presence of an object without causing destruction or damage to the sensing apparatus.

Another object of this invention is to provide a speed measuring apparatus which does not require that the object whose speed is to be measured be accurately thrown or directed.

Still another object of this invention is to provide apparatus for sensing the presence of an object at spaced points to measure its speed which includes at least one gridwork of flexibly mounted sensing members which are adapted to be contacted by the object in flight and permitting the object to pass therethrough.

Another object of this invention is to provide apparatus for determining the speed of an-object which is simple in design, rugged in construction, and capable of continuous operation with a minimum of maintenance.

These and other objects of this invention will become apparent from a reading of the attached description together with the drawings wherein:

Figure 1 is a schematic showing of the appara' tusforming the subject invention;

Figure 2 is a sectional view of one of the gridworks to disclose the relationship of parts;

Figure 3 is a plan view of one of the controlling members operated by the gridwork;

Figure 4 is a sectional view of a plurality of the controlling members showing the electrical connections thereto;

Figure 5 is a circuit diagram of the interval timing apparatus controlled by the gridworks for determining the speed of the object, and

Figure 6 is another embodiment of the invention.

Our invention discloses apparatus for measur ing the speed of an object which has utility as a measuring device and also as a novelty device. As previously noted, present methods of accomplishing such a measuring operation have been too complex, fragile and expensive to have utility particularly as a novelty device. The present apparatus is adapted to measure the speed of a thrown or freely-propelled object, such as a baseball, without requiring a high degree of accuracy in directing the ball. As a novelty device, it is particularly adapted for comparing competitive skills of persons throwing the object. The ruggedness and simplicity of parts in the detecting or sensing portion of the apparatus further permit unlimited consecutive measuring operations without requiring repair or replacements of parts.

As is shown in Figure 1, our invention comprises a pair of gridworks ID and II designed to sense or detect the presence of an object I2 in flight through physical contact with the object and an interval timer means, indicated at 13 3 7 together with a meter I4 to indicate the time required for the object to travel between the gridworks"! and I I. Since the distance between the gridworks III and II is predetermined, the meter I4 indicating the elapsed time can be calibrated in terms of speed of the object.

Gridworks I and II are housed in a frame I5 which rigidly mounts the gridworks II] and II parallel to one another and spaced apart a predetermined distance Y determined by the length of frame I5. The gridworks II) and II are identical and each comprise a plurality of elongated members, I6 and I1 respectively, such as string or wires positioned parallel to one another. Members or wires I6 are each flexibly mounted on a rectangular-shaped frame 2|] of either extremity by springs 2| or other suitable flexure means, as can be seen in Figure 2 and are equidistantly-spaced apart a predetermined distance, indicated at X, which distance is slightly less than the maximum or diametricaldimension of the object I2 or ball whose speed it is desired to measure. Members or wires I6 are made of a material having sufiicient flexibility and strength to withstand direct impact with the object |2 as it is thrown or propelled through the gridworks Ill and H such that they will not break before the mounting spring 2| takes up or absorbs the shock of the impact. The members I6 and I! are also chosen to be of such small diametrical dimension that the object I2 upon impact with one or more of the members IE or I! rolls over its surface and brushes aside said members as it passes through the gridworks II] and II in its flight. By spacing the members I6 and I1 apart the distance X which is slightly less than the diametrical dimension of the object I2, contact with one or two of the members I6 and I1 is insured, irregardless of the position the object I2 passes through the gridworks II] or I. For purposes to be later described, it should be noted that the members I6 and I1 respectively of gridworks It) and II theoretically define a pair of spaced parallel plane surfaces and the various points or point at which the object passes through the respective gridworks define points in space which are spaced apart a, substantially predetermined constant distance Y. Thus, the time interval elapsing durin the travel of the object between the spaced points when related to the distance Y gives a measure of speed of the object I2.

Members I5 and II, as they are contacted by the object I2, move forward or to one side or in a combination of the two directions upon impact. Figure 2 shows in section a portion of gridwork II) with a plurality of control devices 38 thereon which are adapted to be operated by this component of movement of the elongated members I6. The control means 38 are mounted on a bracket 3| suitably secured to the frame of gridwork I9, which mounts the members I6, the bracket 3| being located near one extremity of the members I5, and extending normally there- -to. The plurality of control means are disclosed herein as electrical contact members which are spaced on the bracket 3| to be adjacent to a respective member or wire I6, and suitably attached to the bracket 3|. The control means or contact devices comprise a stationary contact 32 with suitable lead attachment 33 mounted on plate 34 of insulating material and a movable or flexibly mounted contact member 35 similarly attached. The flexibly mounted contact 35, as best seen in Figures 3 and 4,

includes a spring member 36 of electrically conductive material attached at one extremity to the plate 34 remote from stationary contact 32 and having contact element 35 suitably mounted thereon along its extent to contact or engage the stationary contact 32. The spring member 35 extends beyond contact member 35 and is bent into a loop 38 which is adapted to encircle a respective member or wire I6 near one of its spring 2| mounted extremities. By pretensioning the spring members 36, the movable contact element 35 may be made to engage the stationary element 32 in a normal position. Upon impact of the object I2 with one or more of the members I5, said member or members moves forward or to one side, moving or pulling the cooperating spring member 35, and hence the movable contact element 35 away from the stationary contact 32 breaking an electrical circuit therebetween.

The plurality of contact devices 35 or control means are adapted to be connected in a series relationship and in a controlling circuit 48 to be later described so that operation of any of the control means 30, opens the circuit in which they are positioned.

Although not shown, gridwork II has a plurality of contact means 4| associated therewith which are similar to the contacts 3|] of gridwork I3 and are operated in the same manner by the members Il. These contacts are also serially connected in a separate controlling circuit 42 which will be described below.

The controlling circuits 40 and 42 formed by the serially connected contacts 30 and 4| of gridworks It and I I respectively, as shown in Figure 5, include a pair of fast dropout relays 46 and 41 in series therewith, the circuits being energized from a battery source 63. Also included in the energization circuits 4B and 42 for the relays are normally opened contacts 50, 5| of the respective relays 43, 41 which act as holding contacts with a pair of manually operative switches 53, 54 in parallel therewith for resetting or reenergizing the dropout relays 45, 41 when the respective controlling circuits 40, 42 are broken. The energization circuit 40 for the relay 45 is as follows: battery 63, conductor 64, relay 48, holding contact and manual switch 53 in parallel, contacts of control means 30 of gridwork I0 and conductor 65 back to source 63. Relay 4? is con- 1 nected in a parallel relationship with relay 4% and in series with the source 63 as follows: source 63, conductor 64, relay 41, holding circuit 5| and manual switch 54 in parallel, contacts of control means 4| of gridwork I I and conductor 65 to source 63.

The relays 46 and 4'! are utilized herein to control a source of constant current for charging a condenser I0, which charge is a measure of the time elapse between the operation of the relays 46, 41 and hence the time taken for the object I2 to travel between the gridworks I0 and II and operate the respective control means 30, 4| associated therewith. The charge on the condenser I0 provides a controlling bias on a tube TI in one leg of a bridge type measuring circuit I2 unbalancing the bridge circuit and causing meter I4 connected across output terminal I3, I4 of the bridge 12 to indicate bridge unbalance and hence the magnitude of charge. This method of measuring a time interval is a known one, and is disclosed herein as one method of accomplishing this operation. 4

The measuring and indicating apparatus I3 which is shown in Figure 5-will" now be described in detail.

A transformer 15 is connected to the single" phase A.-C. supply for the timing apparatus I3. The transformer 15 has a primary winding I and a center tapped secondary winding 1.! ,the extremities 80, SI of which are connected to. plates 82, 83 of full wave rectifier 84in a conventional rectifier system. Rectifier 04 has its cathode 85 connected across asecondsecondary windingBtof transformer 15. Conductorsflll, S-I which are connectedto the center tapped secondary 1'! and the cathode 85 respectively supply a D.-C. current to the remaining portion of the measuring apparatus. A condenser 8.! connected between conductors 90, 9I operates to smoothand filter this D.-C. input. A resistor 93 connected to conductor 9I at one extremity and to a conductor 94 at the other extremity serves as a droppingresistor for a pair of voltage regulatingv devices 95, 90. The voltage regulating devices 95, 95 are connected in series across. conductors 90, 94 to dividethe voltage supply and regulate the same. Across tube 95 and in a. parallel relation therewith is connected by conductors 94, 98 a pair of resistors I00, I'0I. Resistors I00, IOI are further connected in parallel with a tube 'iI and a resistor I03 in a parallel relationship therewith by conductors 94, 98 to form the Wheatstone bridge circuit T2 with regulating tube 95 serving as the input and a meter I4 connected across output terminals 3, 7 4 between resistors I00, IOI and tube II andiresistor I03 respectively. Tube II is shown a screen grid tube connected as a triode with an anode I05 connected to conductor 94', a cathode I06 connectedto resistor I03,,and-output terminal 74, and a control. grid I01 connected to condenser 10 for purposes which will become evident as this disclosure proceeds.

Also connected in parallel with the bridge '52 described above by conductors 94, 99 are potential dividers I I0, II I in series. Condenser 70 which is connected to control grid I0'I of tube II is connected to a wiper II2 of divider IIO so that divider: I'I0 supplies a control voltage to grid I01 of tube 1! to vary the impedance of tube" permitting it to match the resistances I00, I0-I-, I03 forming bridge '52. Bridge I2 is so constructed that it will normally be balanced with no voltage or current fiow'being impressed on meter I4.

A pentode I having a cathode I2 I, an anode 122, a control grid I23, a screen grid I24 and a suppressor grid I25, has its cathode I2 I" connected to conductor 90 while its anode I22 is connected to condenser I0 and control grid I0'I oftube' "II. Potential divider III has a wiper H3 connected to screen grid I 24, while suppressor grid I25 is connected tov cathode I2I.

Connected across regulating tube 98 are series connected resistors I30, I3I witha resistor I32 connected to their common point at one extremity. Resistor I32 is connected to a rectifying tube I 34 and control grid I23 of tube I20 at itsother extremity. Rectifier tube I34- is further. con nected at its cathode through contacts 530, r3101 relays 46, 4'! respectively to conductor 90 leading to voltage regulating tube 90 and through a resistor I40 to conductor 94 common to voltage regulating tube 95.

Operation The apparatus of the subject invention, when used as a novelty device to determine the speed of a thrown baseball, is generally setas in: the manner disclosed in Figure 1. Canvassidedrops vas backdrop I5I, also shown in phantom,stops the forward movement of the ball after it has passed through the measuring apparatus.

In a normal, or inoperative position, the wires I6, II of gridworks I0, II are untouched and hence the. respective contacts 30, 4I operated thereby are in a normally closed position. The contacts 30, 4I are opened only when the ball I2 or object contacts the wire I6 or I1 associated therewith as it passes:- through the grid-works II), II.

Before each reading or measurement of the speed of theooject, manual switches 53, 54 must be momentarily closed causing the relays 46, 41'

of amplifier I3 to be energized through the circuits described above. When energized, thenormally open contacts 50, 5I of relays 46, 41 respectively are closed setting up holding circuits for the relays after which switches 53, 54 must be opened. The relays 40, 4! will thereafter remain energized until the respective contact circuits 40, 42 of the-gridworks I0, II are broken sequentially by thepassing of the object I2 therethrough. With relays 46, 4'! energized, normally open contact I 36 of relay 46 is made andnormallyclosed contact I31 of'relay 4-1 is open. When the ball or object I2 passes through the respective gridworks- I0, II, the relay 45 isfirst deenergized opening contact I30 and then relay 41 is deenergizedclosing contact I31. When the object or ball I2 has passed through gridwork I0, and has not passed through gridwork II, both of the contacts I35, I31 of relays 49, 4'! respectively will be open. The purpose of this contact arrangement will become evident as the disclosure'proceeds.

The remaining portion of the measuring apparatus I3 is comprised of tube I20 which charges condenser I0 with a constant A.-C. voltage and the bridge circuit 12 which includes as one ofits legs the impedance tube II, the im' pedance of' which is variedby the charge placed on the condenser 10;

The pentode tube I 20, as described above, is connected across the D.-C. supply, and in series with condenser I0 with its grid bias being supplied by currents flowing in resistors I30- and I32. The charging current-of tube I20 is adjusted by the potential on screen grid I24 supplied by voltage divider I I I. Control grid I23 is biased by the voltage drop acrossiresistor I40 and is adjusted to cut off tube I20. Tube I34 serves as a rectifier to limit the direction of current flow through resisters I.30; I32 and I40 biasing tube I20 to maintain this cut off condition. With one or theiother of'the relay contacts I33, I31 closed, current flow is maintained across resistor I40 suflicient to bias the charging tube I20 to cut oif and when both contacts I35, I37 are open, the current flow through. resistor M0 is reduced to zero, so that the'previously adjusted charging current will flow into condenser I0 as long as this-condition of relay operation is maintained.

Tube II forming apart of bridgeIZ is normally biased. through the voltage derived from potenti'ometer I:I.0. such that: its impedance will match resistor I00. andthe bridge'IZ will be in abalance'd condition. The meter I4 will therefore register no signal output from. the bridge.

With tube I20 conducting, that is, under the condition when. the ball: I2; is passing between gridworkslll, II, the charging current of tube I20 will flow into condenser 10 changing the bias on tube II, unbalancing bridge 12 causing an indication of this unbalance on the meter M to register. The rate of change of capacitor voltage caused by the combined action of leakage and grid current is so low'that the drift of the meter I4 is substantially negligible giving ample time for the reading of the meter. Since the charging current can, prior to the measuring operation, be predetermined and the capacity of the condenser Ill be also determined for a given deflection of the meter I4, the time required to charge the con denser 10 to this point can be calculated. This time corresponds to the time elapse between the operation of relays 45, 4! and hence the time taken for the object I2 to travel the predetermined distance Y between the gridworks IB, H. Meter I4, therefore, with these facts known, is calibrated in terms of speed of the object I2 between the gridworks I0, I I.

. Once the measurement is made, relays 45, 47 are placed in an energized condition by the operation of switches 53, 54 andtheseswitches thereafter are opened before the next ball is thrown or the next measurement of speed of the object taken.

The embodiment of the invention disclosed schematically in Figure 6 is similar to the preferred embodiment except that the second gridwork II is modified such that the object I2 does not pass therethrough. As suggested by schematic disclosure of Figure 6, the gridworks l and II are not mounted together in close spaced relationship on a common frame but can be spaced apart a larger predetermined distance by means (not shown) with a spring mounted backdrop I55 located immediately in front of the gridwork II. The parts of the gridworks l0, II remain unchanged and hence will not be described here. The operation of this embodiment is also similar to that of the preferred embodiment with the exception that the object l2 after passing through gridwork II] will strike the backdrop l55 causing it to move slightly forward until one or more of the members I! of gridwork II are contacted thereby operating cooperating contacts 4| therein. Since this embodiment does not require that the object pass through the second sensing device (gridwork II), it will be readily apparent that any other type of controller or arrangement capable of operation by movement of the backdrop may be substituted for gridwork I l.

While the disclosure above is directed specifically to a particular type of apparatus forming a novelty device, it is to be understood that it may have a variety of uses and may take different forms within the meaning of our invention. Therefore, we wish to be limited only b the appended claims.

We claim as our invention:

1. Novelty apparatus for sensing the presence of a thrown baseball at any point on a predetermined plane surface area without interrupting its flight, comprising, a four sided frame member defining the periphery of said plane surface area, a plurality of wire like members of flexible material, a plurality of springs each mounted at one'extremity on'diametrically opposed sides of "said frame member and mounting one of said wire-like members at the other extremity thereof such that said wire like members stretch between said sides of said frame in spaced parallel relationship to define said plane surface area,

said wire like members being spaced apart slightly less than the diametrical dimension of a baseball such that a thrown baseball may pass between said wire like members moving said members slightly apart and slightly forward from their position in said plane surface area, a plurality of contact means mounted on said frame and each including a stationary and a moveable portion biased together in a normal circuit closure position, and means included on each of said moveable portions of said contact means encircling respectively one of said wire like members.

2. Novelty apparatus for sensing the presence of a thrown baseball at any point on a predetermined plane surface area without interrupting its flight, comprising, a frame member defining the periphery of said plane surface area, a plurality of wire like members of flexible material, a plurality of biasing means each mounted at one extremity on said frame member and mounting one of said wire like members at the other extremity thereof such that said wire like members stretch across said frame member between diametrically opposed positions thereon in a spaced parallel relationship to define said plane surface area, said wire like members being spaced apart a distance slightly less than the diametrical dimension of a baseball such that a thrown baseball may pass between said wire like members moving said members slightly apart and slightly forward in the direction of travel of the baseball, and a plurality of contact means mounted on said frame member and adapted to be operated by said wire like members as they are moved in the direction of flight of a, thrown baseball.

3. Novelty-apparatus for sensing the presence of a thrown baseball at any point on a predetermined plane surface area without interrupting its flight, comprising, a frame member having two mounting arms, a plurality of wires positioned to extend between said mounting arms to define said predetermined plane surface area and being spaced apart slightly less than the diametrical dimension of a baseball, a plurality of flexible means for mounting each of said wires at the extremities thereof on said mounting arms, said flexible mounting means permitting said wires when they are contacted by a thrown baseball to move'in the general direction of travel of a thrown baseball providing a passage way for the baseball therebetween without substantially effecting the flight and speed of travel thereof, a plurality of contact means mounted on said frame member and each associated respectively with one of said wires, each of said contact means being positioned normally out of physical contact with said wires and being adapted to be operated by movement of its associated wire when said wire is contacted by a thrown baseball, circuit means connecting said contact means in a series relationship, and means operated by the operation of any one or more of said contact means to indicate the presence of a baseball on the plane surface area.

4. Novelty apparatus for sensing the speed of a thrown baseball between two predetermined plane surface areas without interrupting the flight of the baseball, comprising, a pair of frame members positioned in spaced parallel relationship and separated a predetermined distance, said frame members each having a pair of mounting arms, a plurality of wires positioned to extend between said mounting arms to define the plane surface area, said wires being spaced apart a the baseball there-between without substantially effecting the flight and speed of travel thereof, a plurality of contact means mounted on each of said frame members and each associated with one of said wires, each of said contact means being positioned normally out of physical contact with said wires and being adapted to be operated by movement of its associated wire then the wire is contacted by the baseball, a pair of electrically independent circuits connecting the contact means of each of said frame members in a series relationship, a pair of rapid operating relay members operated respectively by the operation of any one or more of said contact means associated with each of said frame members, a condenser charging circuit operated by the operation of the relay means whose operation is controlled by the circuit associated with the frame member first contacted by the baseball in flight and terminated by the operation of the relay means whose operation is controlled by the circuit associated with the frame member last contacted by the baseball in flight, condenser means connected to said condenser charging circuit, means for measuring the charge on the condenser and determining the time interval during which said condenser is charged, and means converting said time interval into the visual indication of the speed of the baseball between said frame members.

5. Novelty apparatus for sensing the speed of a thrown baseball between two predetermined plane surface areas without interrupting the flight of the baseball, comprising, a pair of frame members positioned in spaced parallel relationship and separated a predetermined distance, said frame members each having a pair of mounting arms, a plurality of wires positioned to extend between said mounting arms to define the plane surface area, said wires being spaced apart a distance slightly less than the diametrical dimension of a baseball, a plurality of flexible means for mounting each of said wires at the extremities thereof on the mounting arms of each of said frame members, said flexible mounting means permitting said wires on each of said frame members when contacted by a thrown baseball to move in the general direction of travel of the baseball and thereby provide a passageway for the baseball there-between without substantially effecting the flight and speed of travel thereof, a plurality of contact means mounted on each of said frame members and each associated with one of said wires, each of said contact means being positioned normally out of p y ical C n with said wires and being adapted to be operated by movement of its associated wire when the wire is contacted by the baseball, a pair of electrically independent circuits connecting the contact means of each of said frame members in a series relationship, a pair of rapid operating relay members operated respectively by the operation of any one or more of said contact means associated with each of said frame members, a condenser charging circuit operated by the operation of the relay means whose operation is controlled by the circuit associated with the frame member first contacted by the baseball in flight and terminated by the operation of the relay means whose operation is controlled by the circuit associated with the frame member last contacted by the baseball in flight, condenser means connected to said condenser and determining the time interval during which said condenser is charged, means converting said time interval into the visual indication of the speed of the baseball between said frame members, and further switching means for operating said pair of relay means to a normally inoperative position.

DONALD F. SHELDON. GEORGE F. JENKINS.

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